Antiside tone circuits



Sept. 15, 1925.

, K. S. JOHNSON ANTISIDE TONE CIRCUITS -Fled Dec. 31 1919 2 Sheets-Sheet l Sept. l5, 1925.

K. s.=JoHNsloN .ANTIS'IDE TONE CIRCUITS .Filed Dec. 31 1919 2 Sheets-fsheet 2 /m/en/or Hennef/7 Jah/75m Patented Sept. 15, 41925.

l UNITED sTATEs PATENT OFFICE.-

KENNETH S. JOHNSON, OF- JERSEY CITY., NEW JERSEY, ASSIGNOR TO WES'IERN ELEC- TRIO COMPANY, INCORPORATED, 0F NEW YORK, N. Y., A. CORPORATION OF NEW YORK.

ANTISIDE TONE CIRCUITS.

Application led December 31, 1919. Serial N'o. 348,507.

To all 'whom t may concernl' Be it known that I, KENNETH S. JOHNSON, a citizen of the United States, residing at Jersey City, in the county of Hudson, State of New Jersey, have invented certain new and useful Improvements in Antiside Tone Circuits, of which the following is a full, clear, concise, and exact description.

This invention relates to vanti-side tone circuits and more particularly to circuits of this type which are adapted for use in telephone substations or two-way repeaters.

It is an object of the invention to provide an arrangement of three or more circuits so related to each other that one of the circuits, which may be called a receiving circuit, willbe responsive to electric impulses set up in another of the circuits, for example, a telephone line, but will not be responsive to electric impulses set up in a third circuit, such as substationtransmitter circuit or the output circuit of a repeater, feeding into the line.

This result has heretofore been accomplished by 'balancing electromotive forces in fluxes producd in the core branches may balance each other. The magnetic forces may be so adjusted that there will be no flux in .one of the core branches and conse'- quently no current in the circuit inductively associated therewith, or they may be so adjusted that the flux in two of the legs may induce equal and opposite M. Fis in one of the circuits, thus rendering it con-, jugate. For a completediscussion ofthe requirements' of a circuit', one portion of which is'conjugate with another, reference is made to U. S. patent to G. A. Campbell, #1,254,471, dated January 22, 1918. n

A wide variety of arrangements employing this invention is possible, only a few of which are shown in the drawings. It may be stated in general that the transformer `core should have at least three branches, each having one or more windings associated therewith. The circuits, usually four in number, are connected to these windings,

of the four circuits is a line, one a telephone receiver circuit or the input circuit of a repeater, one a transmitter circuit or the output circuit of a repeater, and the fourth a line balancing circuit including a resistance or network of impedance simulating the impedance of the line. The latter circuit can be omitted incertain cases where lVhen it is the magnetic reluctance of one branch of the core can be made of a proper value to give the desired balance.

The invention further resides in the details of the circuits herein disclosed, for a full understanding of which reference is hereby made to the following description and claims taken in connection with the accompanying drawings, in which Fig. 1 is a schematic view of a circuit embodying the invention in which tive windings are ein',- ployed; Fig. 2 is a similar view in which the relative position of the transmitter and receiver is reversed; Fig. 3 is a modification of Fig. 1 especially adapted for use as au operators set; Figs. 4, 5 and 6 are modifications ,of Fig. 2 in which less than live windings are employed; Fig. 7 is aview showing the application of the invention to a twoway, one repeater circuit; Fig. 8 isa similar view showing the invention applied to a two-way,two repeater circuit. Figs. 9, 10, `11 and 12 represent variations of the circuit shown'inFig. 1, and Fig. 13 represents the ,circuit ofv Fig. 2 with the balancing network A circuit replaced by the use of a core material for the corresponding leg which has the requisite degree-of 4reluctance tol balance the -line impedance.-

` Referring' to the drawings by reference characters, in Fig. 1 is shown a transformer V.having a core 10 which has legs or branches 11, 12 'and 13.' Ont-heee branches are the windings 16, 17 and 18 respectively. In addition, branch 18 has the winding 19 and erators head set at a central oice.

branch 11 has the winding 20. Connected across winding 16 is theline L; across the winding 17 is the receiver R; across the winding 18 is a line balancing impedance N, and across the two windings-19 and 20 in series isthe transmitter T.

The operation of this circuit is briefly as follows:` When transmitting, alternating currents, having. their source in the transmitter T, flow in the windings 19 and 20, these, in turn, produce magnetic fluxes in the legs 11 and 13. The relation of the impedances of the line L and line balancing impedance N to the number of turns in windings 16, 18, 19 and 20 is such that equal aiding fluxes are induced in branches 11 and 13 of the core. The magnetic forces at the ends of branch 12 are equal, and there is no ux in this branch. Thus, it will be seen that the receiver is anti-side tone or conjugate with respect'to the transmitter.

When receiving currents from the line L,

a flux is induced in the branch 11, which, in

turn, induces currents in. the receiver and transmitter circuits. AThe magnetic flux will be conlined to that portion of the core containing legs 11 and 12. Since the windings 19 and 20 are connected in series, the signal component of the current flowing in the transmitter circuit will set up a magnetic force in branch 13, which will be substantially equal and opposite' to the magnetic force acting in branch 12. There will, therefore, be substantially no flux changes in branch 13, and no energy dissipated in the lbalancing impedance N.

Referring now to Fig. 2, this circuit differs from-F ig. 1 in" that the receiver and transmitter are interchanged. When trans- `mitting, a flux is produced in the branch 12 which divides and Hows in parallel in branches 11 and 13. A This induces equal and opposite E. M. F.s in windings 19 and 2O so that there is substantially no currentin the n receiver circuit, and the energy is dissipated 'rangement of Fig. 1 applied to a two-way in the line L -and the balancing network N. When receiving the current low is substantially the same as in Fig. 1.

In Fi .3 is shown an adaptation of the circuit s own in Fig. 1, for use as `an op- In this circuit an electromagnet receiverr is employed and connections are madejjvhereby current froma common battery 21'can be 'used to energizewboth.the`receiver `and the transmitter. A choke coil 22 )prevents the owof alternating current in the battery circuit and condensers 23 confine the direct windingV 24 .can tbe, conveniently placed on' current toa. simple `circuitin which the re'- celver and thetransmitter are 1n series. A

branch 12 for use asa busy test or for monitorin pur In. lgs. 1 and' 2 the fourrelated circuits.'

are insulated -fromeach other. This is subfunctions of both. In Fig. 6 is shown a circuit dii'ering from the circuit shown in Fig. 5 in that the impedance N is connected in series with windings 18 and 17 and the line L is connected in series with windings 16 and 17 The transmitter circuit is directly connectedto the line thus permitting a common battery to lloe employed toenergize the transmitter.

yThe seriesof circuits `vshown 1n Figs. 2,

4, 5 and 6 represents a transition from a live winding circuit, in which all of the related circuits are insulated from each other, to a three winding circuit in which all of the circuits are directly connected to each other.

AThe operation, however, is essentially the same. In a tive winding circuit, such as that *shown in Figs. 1, 2 and 3, greater freedom is had in selecting impedances for the various elements of the substation circuit; that is to say, the transmitter, receiver and balancing impedancel may be given any desired value regardless o'f the impedance of the line, their effective impedance being readily adjusted by changing the number of the turns in the respective windings. In acircuit, such as that shown in Fig. 6, the impedances of the various substation elements 'must be properly chosen with reference to each other and the line in order to obtain the greatest efficiency. e

In Fig. 7 is shown the transformer arrepeater in which a single repeater element is employed.Y The input circuit of the' vacuum tube repeater 25 is connected across the output of,y the repeater is connected across the windings 19 and 20 in place of the transmitter T. In this type of repeater, instead'of a line L and balancing resistance N, the two lines L, and L2 are made eifec- (tively, to balance each other. For example, current coming in from line L1 induces a current in the input circuit of the repeater, vand the ampliedk current Vpassing through fwindings19 and 2O produces a series aiding Aiux in branches 13 and 11 and corresponding currents in thelines L1 and L2. If the relation of the im edances of lines L1 and line L2 to the-num r of turns in windings 16, 18, 19 and`20 is properly chosen no current will be induced in the winding 17 as the result of the amplified current. There will accordingly be substantially no tendency for the repeater to sing.

In Fig. 8 the same transformer arrangement is shown applied to a two-way repeater circuit having two oppositely directed repeaters. In this case transformers 26 and 27 are provided for lines L1 andL2 respectively, and balancing networks N1 and N2 are associated with vthe respective lines. The input circuit of repeater 29 is connected across the winding 17 of a transformer 26, while its output circuit is connected across the windings 19 and 20 of the transformer 27. 'In a similar way repeater 30 has its input circuit associated with the middle branch of the transformer 27 and its output circuit with the outside branches of the transformer26. Filters F1 and F2 may be interposed in the output circuits to oo ntrol made to U. S. patent to B. W. Kendall the frequency range of the currents transmitted.

The effective impedances of balancing networks N1 and N2 are made equal to the impedances of the respective lines. The output energy of each of the repeaters is divided between the corresponding line and balancing network and substantially none of it is fed back into the input of the other repeater. For a comparison of the circuit of Fig. 8 with a circult employing electrical balance for a similar purpose, reference is 7 #1,216,136, dated February 13, 1917.

Figs. 1 and 3 represent a circuit which has been found from actual tests as a substation circuit to be very satisfactory. This circuit has therefore been -chosen as the preferred form of the invention for the purpose of this application. It is apparent, however, from Figs. 1, l2, 9, 10, 11 and v12 that anti-sidetone circuits may be designed in which the four associated circuits are'interchanged in a great number of ways. Not all of the ve winding'circuits are shown, but it vis believed that the number is sufficient to give a full understanding of the nature of the invention. Corresponding variations may of course be made with the four winding and three winding circuits. v

As above stated the balancing impedance or network may be omitted and the corresponding leg of the transformer core made wholly or partly of a material vhaving a lower permeability than the other portions of the core. The effective reluctance may also be increased b decreasing the crosssectional area of this branch. An example of this type of circuit is shown in Fig. 13. When transmitting with this circuit, the flux generated in branch 12` divides between branches 11 and 13 in such a Way that equal and opposite E. M. F.s are induced in the windings 19 and 20.

In none of the circuits shown has there been any attempt to show the ratio of turns of one winding with reference to another, since this ratio will depend on the impedance of the associated elements and in lsome cases on the direction of the windings. Only in the case ofv windings 19 and 20,.do the drawings purport to show the necessary direction of windings, since in most instances the direction of winding may be reversed.

In certain of the following claims the expression line balancing circuit is to be taken to include a real line for balancing nother real line as well as an artificial linel or this purpose.

What is claimed is:

1. .A two-way signaling system compris'in a magnetic core having three legs, a win ing on each of said legs, a line circuit and at least two other circuits connected to said windings, said line circuit and at least one of said other circuits each being connected directly across two of said windings respectively.

2. A two-way signaling system comprising a magnetic core having three legs, wmdings on said legs, and two pairs of circuits con- .nected to said windings, the circuits of each pair being conjugate to each other, one cir-v cuit of each pair being receptive to currents produced in a circuit of the other palr.

3. A two-way signalingsystem comprising a magnetic core having three legs, a winding on each of said legs, a line circult, a receiving c1rcu1t and atransmittmg circuit 'connected to said windings, at least two of said circuits each being connected directly across two of said windings respectively, said .re-

ceiving and transmitting circuits being substantially conjugate.

4. A two-way signaling system comprising a magnetic core having three legs, a winding on each of said legs, a line circuit, a receiving circuit and a transmitting circuit connected to said windings, said receiving and line circuits each ,being connected directly across two of said windings respectively.

5. A two-way signaling system comprising a magnetic core having three legs, a winding on each of said legs, a line circuit, a line balancing circuit, a receiving circuit and a transmitting circuit connected to said windings, at least two of said circuits each being connected directly across two of said Windings respectively.

6. In combination, a magnetic core having at leastthree branches, a line circuit, a transmitting circuit, a receiving circuit, and

Aa line balancing circuit, each of said circuits circuits being conjugate.

y V7. In combination` a magnetlc core having at least three branches, windings on said branches, receiving, transmitting, line and line balancing circuits, connected to said netic core having three branches, transmitwindings, at least one of said circuits being connected across two of said windings.

8. In a two-way signaling system, a magnetic core having at least three branches, receiving, transmitting, line and line balancing circuits, three of said circuits each having a winding on a corresponding leg of said core, the other of said circuits having a winding on each of two of said legs.

9. In a two-way signaling system, a magnetic core having at least three branches, receiving, transmitting,- line and line balancing circuits, three of said circuits each having a winding on a corresponding leg of said core, the other of said circuits having a winding on each of two of said legs, said circuits being effectively insulated from each other. y

10. In a two-way signaling system, a magnetic core having three branches, a winding on one branch, two windings on each of the other branches, a receiver connected across said rst winding, a transmitter connected across two windings one on each of the other branches, a line and balancing network connected across the remaining two windings respectively.

11. In a two-way signaling system, a magnetic core having at least three branches, receiving, transmitting, line and line balancing circuits, three of said circuits having a winding on a corresponding leg of said core, the other of said circuits having a winding on each of two of said legs, said circuits being effectively insulated from each other and a common battery supplying direct current to said receiving and transmitting circuits.

12. In a two-way signaling system, a magting, receiving and line circuits having windings on, said branches, and a monitoring windingi on one of said branches.

13. In agtwo-way signaling system, a magnetic corefhaving three branches, transmitting, receiving and line circuits having windings on said branches, and a monitoring winding on the branch having-the receiving circuit winding.

14. A two-way signaling system comprising a magnetic'core having three legs. at least four windings on said legs, one of said windings having a part thereof on one of said legs and another part thereof on another of said legs at least three circuits connected to said windings, one of said circuits being responsive to electric impulses set up in another of said circuits, said first circuit being substantially unresponsive to electric impulses set up in a third of said circuits.

15. A two-way signaling system comprising a magnetic core having three legs, at.

least four windings onsaid legs, at least four circuits connected to said windings, one of said circuits being responsive to electricimpulses set up in another of said circuits, said first circuit being substantially unresponsive to electric impulses set up in a third of said circuits.

16. In combination, a magnetic core having three legs, a circuit having windings on only two of said legs, a second circuit having a winding on at least one of said two legs and being insulated from any windings on the third of said legs and a third circuit having a wind/ing on the third of said legs, said rst and third circuits being conjugate.

17. The combination with a telephone line circuit of a substation set comprising a circuit comprising 'a telephone transmitter, a second 'circuit comprising a telephone receiver and a magnetic core having three legs and a winding on each leg, at least two of said circuits each being connected directly across two of said windings respectively, the transmitting and receiving circuits being l substantially conjugate.

18. The combination with a telephone line circuitof a substation set according to claim 14, in which the windings on said core are so proportioned that the impedance of said substation set as seen from theline, is subtantially equal to the impedance of said 19. The combination with a telephone line circuit of a substation set comprising a telephone transmitter, a telephone receiver, a line balancing circuit and a magnetic core having three legs, said transmitter and receivervand each of saidcircuits being magnetically related to said core, said line and said line balancing circuit being conjugate, and said telephone transmitter and said telephone receiver beingconjugated.

20. In `combination a magnetic core having at least three branches, windings on said branches, receiving, transmitting, line, and line balancing circuits connected to said winding at least one of said circuits being connected across two of said windings in series.

In witness whereof, I hereunto subscribe my name this 30th day of December, A. D.

KENNETH S. JOHNSON. 

